Required clearance, between multiple flues.

Is it â€œokâ€ to vent a water heater and 2 gas Furnaces through a roof side by side? The vents would be Spaced about 3â€™ apart from each other? One would be gravity and the second would be Induced type â€œBâ€, and the third would be Induced â€œPVCâ€.

Each manufacturer will have very specific directions in their installation manual about proximity of air intake to other (and their own) exhaust plus a relationship to operable windows and other obstructions. You need to consult those manuals for specific instructions.

Each manufacturer will have very specific directions in their installation manual about proximity of air intake to other (and their own) exhaust plus a relationship to operable windows and other obstructions. You need to consult those manuals for specific instructions.

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Yes the instructions are quite specific. It says: â€œMust be vented in accordance with ANSI Z223.1â€

Most I've dealt with have numerous pictures and drawings in the installation manual (not in the owner's manual) describing the do's and don'ts. Haven't tried searching for that spec...it might be on-line.